• Agent-based Discovery:
  • Involves installing software directly on OT devices.
  • Offers detailed information about the device itself, including operating system and applications running.
  • Downside: Disruptive to OT operations, requires additional resources on devices, and may not be compatible with all OT equipment.
• Agentless (Passive) Discovery:
  • Analyzes network traffic to identify and characterize devices.
  • Less intrusive and preferred method for OT security as it avoids disrupting critical operations.
  • Downside: May not provide the same level of detail as agent-based discovery, particularly for isolated devices or those with limited network communication.

A comprehensive OT asset inventory provides the foundation for a robust cybersecurity strategy. By knowing exactly what devices are connected to your network, you can:

• Identify and prioritize vulnerabilities: Knowing the types and versions of devices on your network allows you to identify known vulnerabilities and prioritize patching efforts for the most critical assets.
• Minimize your attack surface: With a complete inventory, you can eliminate unnecessary devices and connections from your network, reducing potential entry points for attackers.
• Enhance threat detection and response: Faster identification of compromised devices during a security incident allows for quicker isolation and mitigation of damage.

Beyond security advantages, asset discovery offers valuable insights for optimizing OT network management. It allows you to:

• Streamline maintenance planning: Having a detailed registry of devices and their criticality helps to plan maintenance activities more effectively, reducing downtime and associated costs.
• Improve resource allocation: By understanding the types and capabilities of your OT devices, you can allocate resources more efficiently to support ongoing operations.
• Facilitate system upgrades: A complete asset inventory helps ensure compatibility when implementing new technologies or upgrades within the OT network.

The heterogeneous nature of OT environments, with different devices and communication protocols, can complicate discovery efforts. Here are some strategies to address this:

• Segmentation: Divide your OT network into segments based on device type, function, or security level. This allows for targeted discovery approaches tailored to each segment.
• Leverage Standardized Protocols: If possible, migrate OT devices to use standardized communication protocols like SNMP (Simple Network Management Protocol) to simplify discovery and management.
• Utilize Specialized Tools: Consider specialized asset discovery tools designed for OT environments, which can handle diverse protocols and provide deeper insights into device functionality.

OT environments are dynamic, with new devices being added or removed regularly.  Therefore, a continuous or periodic rediscovery process is necessary. Here's how to approach it:

• Initial Discovery: Perform a comprehensive initial discovery to establish a baseline inventory of all OT assets.
• Continuous Monitoring: Implement tools for ongoing network traffic analysis to capture new devices and changes in existing ones.
• Scheduled Rediscovery: Schedule periodic full rediscovery scans at regular intervals (e.g., quarterly) to ensure complete and accurate asset information.